cpu_map: Define md-clear CPUID bit

CVE-2018-12126, CVE-2018-12127, CVE-2018-12130

The bit is set when microcode provides the mechanism to invoke a flush
of various exploitable CPU buffers by invoking the VERW instruction.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
(cherry picked from commit 538d8735)

Conflicts:
	src/cpu_map/x86_features.xml
            - no CPU map split downstream

	tests/cputestdata/x86_64-cpuid-Xeon-Platinum-8268-guest.xml
	tests/cputestdata/x86_64-cpuid-Xeon-Platinum-8268-host.xml
            - test data missing downstream

	tests/cputestdata/x86_64-cpuid-Xeon-E3-1225-v5-guest.xml
	tests/cputestdata/x86_64-cpuid-Xeon-E3-1225-v5-host.xml
            - intel-pt feature is missing downstream
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

src/cpu/cpu_map.xml

@@ -295,6 +295,9 @@
     <feature name='avx512-4fmaps'>
       <cpuid eax_in='0x07' ecx_in='0x00' edx='0x00000008'/>
     </feature>
+    <feature name='md-clear'> <!-- md_clear -->
+      <cpuid eax_in='0x07' ecx_in='0x00' edx='0x00000400'/>
+    </feature>
     <feature name='spec-ctrl'>
       <cpuid eax_in='0x07' ecx_in='0x00' edx='0x04000000'/>
     </feature>

tests/cputestdata/x86_64-cpuid-Xeon-E3-1225-v5-enabled.xml

@@ -2,7 +2,7 @@
 <cpudata arch='x86'>
   <cpuid eax_in='0x00000001' ecx_in='0x00' eax='0x00000000' ebx='0x00000000' ecx='0xf7fa3203' edx='0x0f8bfbff'/>
   <cpuid eax_in='0x00000006' ecx_in='0x00' eax='0x00000004' ebx='0x00000000' ecx='0x00000000' edx='0x00000000'/>
-  <cpuid eax_in='0x00000007' ecx_in='0x00' eax='0x00000000' ebx='0x009c4fbb' ecx='0x00000000' edx='0x8c000000'/>
+  <cpuid eax_in='0x00000007' ecx_in='0x00' eax='0x00000000' ebx='0x009c4fbb' ecx='0x00000000' edx='0x8c000400'/>
   <cpuid eax_in='0x0000000d' ecx_in='0x01' eax='0x00000007' ebx='0x00000000' ecx='0x00000000' edx='0x00000000'/>
   <cpuid eax_in='0x80000001' ecx_in='0x00' eax='0x00000000' ebx='0x00000000' ecx='0x00000121' edx='0x2c100800'/>
 </cpudata>

tests/cputestdata/x86_64-cpuid-Xeon-E3-1225-v5-guest.xml

@@ -19,6 +19,7 @@
   <feature policy='require' name='osxsave'/>
   <feature policy='require' name='tsc_adjust'/>
   <feature policy='require' name='clflushopt'/>
+  <feature policy='require' name='md-clear'/>
   <feature policy='require' name='stibp'/>
   <feature policy='require' name='ssbd'/>
   <feature policy='require' name='xsaves'/>

tests/cputestdata/x86_64-cpuid-Xeon-E3-1225-v5-host.xml

@@ -20,6 +20,7 @@
   <feature name='osxsave'/>
   <feature name='tsc_adjust'/>
   <feature name='clflushopt'/>
+  <feature name='md-clear'/>
   <feature name='stibp'/>
   <feature name='ssbd'/>
   <feature name='xsaves'/>

tests/cputestdata/x86_64-cpuid-Xeon-E3-1225-v5-json.xml

@@ -5,6 +5,7 @@
   <feature policy='require' name='hypervisor'/>
   <feature policy='require' name='tsc_adjust'/>
   <feature policy='require' name='clflushopt'/>
+  <feature policy='require' name='md-clear'/>
   <feature policy='require' name='stibp'/>
   <feature policy='require' name='ssbd'/>
   <feature policy='require' name='pdpe1gb'/>